London Metropolitan Police/AP

British police are reportedly honing in on a trio of cleaners who were burgling holiday villas in Praia da Luz, Portugal just weeks before Madeleine McCann disappeared in 2007. McCann, who was almost four at the time, was asleep in her parents’ holiday apartment with her younger twin siblings while her parents dined at a nearby tapas bar. The McCanns and their dinner companions took turns checking on the children at regular intervals, which apparently gave whoever snatched the child an ample window to break in and steal away with her. British Metropolitan police, who reopened the case in 2012 have confirmed that they sent an “International Letter of Request” to Portuguese officials, presumably paving the way to arrest the three men on suspicion of kidnapping.

The breakthrough stems from a thorough review of the original Portuguese investigation dossier by Scotland Yard under the code name Operation Grange. The review uncovered nearly 200 leads that the Portuguese failed to follow up on and identified 40 persons of interest, including the three cleaners. According to documents released by Scotland Yard, the trio of cleaners had been allegedly breaking into holiday villas in April 2007, a month before McCann disappeared. They even reportedly disturbed a sleeping child during one of their break-ins, prompting the parents, who were sitting on the villa balcony, to chase them away and report it to the police.

Scotland Yard detectives are particularly interested in finding out why the three men, whose names are known to police but have not been released to the public, made multiple phone calls to each other in the moments and days after McCann disappeared, which was an anomaly when detectives checked the dates against their previous phone activity. British police want to know what was so urgent that caused them to spend so much time on the phone with each other.

Portuguese police knew of the burglaries, but apparently did not find it relevant to their own original investigation. Immediately after McCann’s disappearance, they had focused on McCann’s parents, Kate and Gerry, as their prime suspects, failing to follow up on hundreds of potentially useful leads. A representative for the McCanns told a British newspaper that the pending arrests don’t necessarily prove the cleaners have the child, but it could provide them with crucial information. “The letter is a significant development. It is necessary for British police to request the Portuguese authorities allow them to operate on their turf. It means they have the intention of arresting and interviewing X, Y or Z. We don’t know who they have their sights on but it’s likely it is the burglars,” according to a McCann spokesman quoted by the Daily Mail. “Whether the Portuguese will cooperate remains to be seen. It is a very sensitive issue with all the differences they have had.”

Portuguese police have not been forthcoming with British police in the past, but they did reluctantly reopen their case in late 2013 at Scotland Yard’s urging. The Portuguese authorities closed their investigation into McCann’s disappearance in 2008 after releasing McCann’s parents as their only suspects. They still have to grant permission for British authorities to make arrests or question suspects in Portugal. A number of British newspapers reported that a team of British detectives is en route to Portugal, presumably to make the initial arrests.

The new lead comes just months after Scotland Yard released two e-fit composite images of their prime suspect, a white man between the age of 20 and 40 who matches the description of dozens of witnesses who were in the complex when McCann disappeared. Shortly after the e-fits were released, the Portuguese authorities then named their own suspect, Euclides “Toni” Monteiro, a 40-year-old heroin addict from Cape Verde who had died in a tractor accident four years ago.

The imminent arrest of the three burglars, whose whereabouts have not been made public, would be the first arrests in the puzzling case.